1. Field of the Invention
The present invention relates to an automatic door sensor device that detects an object to control opening and closing of a door.
2. Description of Related Art
In general, a microwave sensor is often used for detecting the entry of an object such as a human body into a detection area. As a result of this detection, an automatic door is opened. In order to ensure the safety of an area on the track of the door or on the path of movement of the door, an infrared sensor is used to detect an object in a doorway area which includes at least a portion of the area defined by the path of the door, and the door is kept open until the object leaves the doorway area.
In the automatic door sensor device, the microwave sensor may erroneously recognize the closing door as a moving object in the case that the detection area of the microwave sensor overlaps with the area on the track of the door. In order to prevent the object from being jammed in the door, the automatic door sensor device tries to open the door even though no object is present in the area on the track of the door because the closing door has been detected as an object. For the purpose of preventing such a malfunction, the detection area of the microwave sensor is usually defined so as not to overlap with the area on the track of the door (e.g., see Japanese Unexamined Patent Application Publication No. 2004-239755).
However, the detection area of the microwave sensor, or in other words, the limit within which an object can be detected by the microwave sensor cannot be readily perceived. For this reason, the detection direction of the microwave sensor is set outward away from the area on the track of the door in order to ensure that the detection area of the microwave sensor will not overlap with the area on the track of the door.
On the other hand, a microwave sensor that uses the Doppler effect and an infrared sensor employ different object detection techniques, and therefore, only one of these sensors may be able to detect an object in some circumstances. For this reason, it is desirable that the detection area of the microwave sensor is close to or overlaps with the doorway area, and consequently overlaps with the detection area of the infrared sensor, which covers the area in the vicinity of the doorway or the area vertically above the track of the door. Accordingly, it is desirable not only to prevent erroneous detection while the door is transitioning from an open position to a closed position, but also to make these detection areas overlap.
Further, in the event that a transom that supports the door sways while the door is transitioning from an open position to a closed position, the infrared sensor mounted on the transom may malfunction and the automatic door sensor device may try to open the door in order to prevent an object from being jammed in the door, even though there is no object in the area. If the infrared sensor is configured in terms of preventing this malfunction, the infrared sensor would fail to detect an object in a normal detection operation.
Therefore, an object of the present invention is to provide an automatic door sensor device capable of preventing erroneous detection of the door transitioning from an open position to a closed position as an object by temporality changing the detection area.